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21.
22.
Kitagawa O Miyaji S Yamada Y Fujiwara H Taguchi T 《The Journal of organic chemistry》2003,68(8):3184-3189
Treatment of N-tosyliodoaziridine derivatives with Et(3)B efficiently produces various azahomoallyl radical (2-akenylamidyl radical) species which give oxygen-functionalized pyrrolidine derivatives through iodine atom transfer [3 + 2] cycloaddition with electron-rich alkenes such as enol ethers and ketene acetal. The present cycloaddition reaction proceeds regioselectively via C-N bond cleavage of an aziridinylalkyl radical intermediate and addition of the resulting azahomoallyl radicals to the terminal carbon of an alkene. The reaction of alkenes with the cyclohexenylamidyl radical generated from an optically active bicyclic iodoaziridine [(1S,2S,6S)-2-iodo-7-(p-toluenesulfonyl)-7-azabicyclo[4.1.0]heptane, 94% ee] also proceeds to give optically active octahydroindole derivatives (84-93% ee). 相似文献
23.
The salts of trialkoxybenzoic acids and 2-amino alcohols showed a columnar liquid crystalline phase; in the case of the salt of a polymerizable acid and norephedrine, the photopolymerization proceeded efficiently in the liquid crystalline state, and the resultant solid adsorbed 2-amino alcohols size, regio-, and enantio-selectively. 相似文献
24.
The submillimeter-wave rotational transitions of HOC(+) in the nu(2) excited state are first detected using the double-modulation method, and the precise transition frequencies and the much improved molecular constants are obtained. The measurements of the ground state HOC(+) and DOC(+) submillimeter-wave lines are extended up to the 840-GHz region. It is found that the higher order centrifugal distortion constant, H, is necessary to fit the observed transition frequencies to the experimental accuracy. Copyright 2000 Academic Press. 相似文献
25.
M. Sabooni M. Esmaeili H. Haratizadeh B. Monemar P. Paskov S. Kamiyama M. Iwaya H. Amano I. Akasaki 《Opto-Electronics Review》2007,15(3):163-167
We report results from optical spectroscopy such as photoluminescence (PL) and time resolved photo-luminescence (TRPL) techniques
from different well width MOCVD grown GaN/Al0.07Ga0.93N MQW samples. There is evidence of localization at low temperature in all samples. The decay time of all samples becomes
non-exponential when the detection energy is increased with respect to the peak of the emission. Localization of carriers
(excitons) is demonstrated by the “S-shape” dependences of the PL peak energies on the temperature. The time-resolved PL spectra
of the 3-nm well multi quantum wells reveal that the spectral peak position shifts toward lower energies as the decay time
increases and becomes red-shifted at longer decay times. There is a gradient in the PL decay time across the emission peak
profile, so that the PL process at low temperatures is a free electron-localized hole transition. 相似文献
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28.
Yohjiro Kawai Shinya OhsukaMotoaki Iwaya Satoshi KamiyamaHiroshi Amano Isamu Akasaki 《Journal of Crystal Growth》2009,311(10):2929-2932
We have demonstrated InxGa1−xN epitaxial growth with InN mole fractions of x=0.07 to 0.17 on an m-plane ZnO substrate by metalorganic vapor phase epitaxy for the first time. The crystalline quality of the epilayers was found to be much higher than that of epilayers grown on a GaN template on an m-plane SiC substrate. 相似文献
29.
Amano T 《The Journal of chemical physics》2010,133(24):244305
The J = 1-0 transitions of (12)CH(+), (13)CH(+), and (12)CD(+) in the ground X(1)Σ(+) state have been unambiguously identified by using an extended negative glow discharge as an ion source. Unexpectedly large Zeeman splittings have been observed, and the (13)CH(+) line exhibits nuclear spin-rotation hyperfine splitting in addition to the Zeeman effect. The nuclear spin-rotation coupling constant was determined to be 1.087(50) MHz for the (13)C species. The rotational g-factor is found to be -7.65(29), in terms of the nuclear magneton for the J = 1 and v = 0 state, more than an order of magnitude larger than values for typical diamagnetic closed shell molecules. These larger than usual magnetic interactions for a (1)Σ molecule are caused by the large rotational energy and relatively small excitation energy of the excited A(1)Π state. The effective g-factor and the spin-rotation coupling constant obtained by ab initio calculations agree very well with the experimentally determined values. 相似文献
30.
Shinsaku Dobashi Masaharu Kira Ryuichiro Tanaka Yoshinori Izawa Akihide Wada Michikazu Hara 《Analytical sciences》2006,22(4):603-606
The development of molecular spectroscopy has enabled us to select chlorinated aromatic hydrocarbons very rapidly. In particular, the laser ionization TOFMS (time-of-flight mass spectrometry) method is expected to be useful as an on-line, selective, and sensitive method. In the present work, real-time laser ionization TOFMS measurements were carried out on gaseous chlorinated aromatic hydrocarbons. The laser ionization method used resonance-enhanced two-photon ionization with the direct introduction of gas into the vacuum chamber. This method for analyzing aromatic hydrocarbons was developed using a pulsed supersonic molecular beam method. In the context of developing a highly selective and sensitive method, excitation of monochlorinated benzene at lambda = 263.07 nm was found to be effective in the wavelength region from 263 nm to 265 nm. Also the excitation of polychlorinated biphenyls at lambda = 266 nm was found to be substantially more effective than at lambda = 280, 300 or 320 nm. The achievable sensitivity for real-time (1 min) measurements using the laser ionization TOFMS technique was found to be in the ppbV range. 相似文献